The present invention relates to a telescoping length extendable device such as a tower, an antenna, carrier, carrier arms, manipulator arms or the like which include telescoped, and relatively movable elements as well as advancing/retracting driving means to obtain extension and retraction of the device.
Generally speaking, one of the simpler kinds of telescopic arrangements, are tripods known to have longitudinal, telescoping legs, and wherein the elements of a leg are protracted or pushed back manually. Force is always exerted on the innermost elements for either deployment or collapse, and these elements are coupled to the others so as to move, one by one, in one direction or the other. The relative motion of the individual telescoping elements is permitted as well as limited through stops and resilient latching structure. This kind of arrangement does not generally insure a positive sequence of operation rather the sequence and degree of movement may even vary from instance to instance. This is usually not a disadvantage for working simple tripods for photography or the like, although, inbetween positions may at times be difficult to attain. However, in some instances it is desirable to make sure that there is a definite sequence in the relative motion and extension.
The following requirement may exist. It may be assumed that a basic position obtains when all elements are completely nested and telescoped into each other. Now, the requirement is posed that the outermost one is to be moved first, then the next one, with the innermost element being the last to move. This means that the outermost latch must release more easily, i.e. must be released while latching is maintained in and for the more inner ones of the elements.
German Pat. No. 26 03 488 provides for a construction of telescopic tubes, wherein the innermost one is moved out first while the others are retained, then the next one is moved out and so forth with a positive sequence being maintained from inner to outer tubes. These known devices are provided with bridgable latches and springs, whereby the spring bias differs for the different latches--different in terms of strength that varies from the inner to the outer latches.
The Swiss Pat. No. 53 534 discloses a device with telescopic tubes of variable or different cross section and the patent described coupling and latching structure, being comprised of a spring loaded bolt or pin and a transverse lock. The latter lock runs in grooves which are provided to shift the pin into a particular bore so as to obtain a coupling relation between two tubular elements. The head part of the pin or bolt abuts the next one of the tubular elements. This abutment obtains through a spring, insertion and retraction pressure is exerted in and along the axis of the equipment. This mode of operation, however, leads to excessive friction. Considering the forces that may act on a fully deployed antenna mast galling may actually occur as well as carving or cutting-like operations.
German printed patent application No. 35 22 386 describes a telescopic device with a plurality of nestedly telescoped tubular elements, a drive is provided for retraction or protraction (or deployment), acting on the inner one of the tubular elements. There is a latching structure for blocking the individual tubular elements in relation to each other. The drive in this instance is a very time consuming one because the particular body acting on the latching device for each individual tubes has to be positioned in the uppermost position if deployment and extension is to obtain from completely retracted position in which all the coupling elements on the lowermost position. Once this particular piece hs been placed in the outermost position it has to be returned so as to obtain the operation of the next tubular element. This back and forth movement is time-consuming. The utilized elements of the latching structure, particularly the spring elements employed, are unsuitable for cooperation with larger loads unless the spring force is made so large that the pins and bolts require excessive force for abutment against the tube such that in fact deformations or cuttinglike interaction may occur.